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Description of key information

Acute oral toxicity (similar to OECD TG 401): LD50 = 1060 mg/kg bw (for females being the lower value. For males the LD50 males = 2000 mg/kg bw)

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
Reference
Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 20, 1980 - April 5, 1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
Version / remarks:
Study performed prior to introduction of guideline
GLP compliance:
no
Test type:
standard acute method
Limit test:
no
Species:
rat
Strain:
other: TacN(SD)fBR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Farms (Germantown, N.Y.)
- Females (if applicable) nulliparous and non-pregnant: no information
- Age at study initiation: young adult
- Weight at study initiation: 180-280 grams
- Fasting period before study: overnight
- Housing: individually in wire cages under standard laboratory conditions
- Diet (e.g. ad libitum): ad libitum, Purina Rodent Laboratory Chow 5001
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 7 days

Route of administration:
oral: gavage
Vehicle:
ethanol
Remarks:
SDA 39C
Details on oral exposure:
VEHICLE
- Concentration in vehicle: Appropriate for each dose level

MAXIMUM DOSE VOLUME APPLIED: 5.0 ml/kg bw

STARTING DOSE:
- Rationale for the selection of the starting dose: a preliminary dose range finding study was done to determine mortality. Two fasted rats (one male one female) were used per dose, administered the test substance and observed for the next 72 hours to determine mortality. At the initial dose of 5.0 g/kg bw, both male and female rat died. Subsequently doses of 0.1, 0.5 and 1.0 g/kg bw were used and all rats survived.
Doses:
1.0, 1.4, 1.8, 2.4, and 3.2 g/kg bw in males and females.
Additional groups of females only 0.63, 0.79, 1.0, 1.26 and 1.59 g/kg bw.
No. of animals per sex per dose:
8
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: the animals were observed at 1, 3, 5 and 24 hours after application and thereafter twice daily (once daily on weekends).
- Necropsy of survivors performed: yes, at the end of the observation period the animals were killed by ether inhalation, necropsied and subjected to examination for gross pathological changes.
- Body weights: Individual body weights were recorded before fasting, immediately before treatment and then on the 14th day of the observation period.
Statistics:
According to J.T. Litchfield, Jr. and F. Wilcoxon, 1949, 'A Simplified Method of Evaluating Dose-Effect Experiments', J. Pharm. Exp. Therap., 96:99-115.
Preliminary study:
Range finding study in 2 rats: the initial dose was 5.0 grams per kilogram body weight and both rats died. Subsequenty doses of 0.1, 0.5 and 1.0 g/kg were used and all rats survived.
Key result
Sex:
female
Dose descriptor:
LD50
Effect level:
1 060 mg/kg bw
Based on:
test mat.
95% CL:
>= 853 - <= 1 318
Key result
Sex:
male
Dose descriptor:
LD50
Effect level:
2 000 mg/kg bw
Based on:
test mat.
95% CL:
>= 1 535 - <= 2 606
Mortality:
Mortality rate in males per dose: 1/8 (1.0 g/kg), 3/8 (1.4 g/kg), 4/8 (1.8 g/kg), 2/8 (2.4 g/kg) and 7/8 (3.2 g/kg).
Mortality rate in females per dose (first group): 4/8 (1.0 g/kg), 8/8 (1.4 g/kg), 7/8 (1.8 g/kg), 7/8 (2.4 g/kg) and 8/8 (3.2 g/kg).
Mortality rate in females per dose (second group): 1/8 (0.63 g/kg), 5/8 (0.79 g/kg), 7/8 (1.0 g/kg), 8/8 (1.26 g/kg) and 5/8 (1.59 g/kg).
Clinical signs:
At the lowest dose 1.0 g/kg in males and 0.63 g/kg in females, animals were prone or ataxic for the remainder of the day after dosing. Survivors recovered in the next day and appeared normal from day two and three, respectively, for the remainder of the study. At higher doses, similar signs occured and soft stools were relatively frequent. Less frequent signs were chromodacryorrhea, clonic convulsions and wetness of the fur around the mouth.

In general, clinical signs observed included ataxia, lacrimation, prone position, tremors, lethargy, chromodacryorrhea, twitches/jerks, unkempt fur, chromorinhorrhea, piloerection, abdominal gripping, diarrhea, moribund, hyperresponsiveness to external stimuli, hematuria and oral discharge.
Body weight:
All surviving animals gained weight in a normal pattern.
Gross pathology:
No signs of systemic toxicity were found in any animal necropsied at termination. Common signs in animals that died were yellow fluid in the stomach (probably test article) and reddish fluid in the intestines. In two animals red lining of the intestines is observed from which one animal also showed red lining of the stomach. Furthermore in one animal black fluid in the intestines was observed and in one animal autolysis of tissue in other than standard examined tissues.

Dosage (g/kg)

Mortality males

Mortality females (first group)

Mortality females (second group)

All surviving animals were normal by day

0.63

 

 

1/8

3

0.79

 

 

5/8

5

1.0

1/8

4/8

7/8

All but one on day 2, one on day 5

1.26

 

 

8/8

 

1.4

3/8

8/8

 

2

1.59

 

 

5/8

4

1.8

4/8

7/8

 

3

2.4

2/8

7/8

 

All but one on day 2, one on day 3

3.2

7/8

8/8

 

2

Interpretation of results:
other: Acute Oral Toxicity, Category 4
Remarks:
in accordance with EU CLP (EC 1272/2008 and its updates)
Conclusions:
The calculated acute oral LD50 for males was 2000 (95% Cl 1535-2606) mg/kg bw, and the calculated acute oral LD50 for females was 1060 (95% Cl 853-1318) mg/kg bw. Based on the results of this study it is concluded that Dimeth Cyclormol should be classified as harmful if swallowed.
Executive summary:

An acute oral toxicity study was performed according to a method similar to OECD TG 401, not under GLP and therefore receives Kl. 2. In this study, 80 rats (40 males and 40 females) were administered Dimeth Cyclormol at dose levels of 1.0, 1.4, 1.8, 2.4, and 3.2 g/kg bw resulting in mortality rates of 1/8, 3/8, 4/8, 2/8, and 7/8 for males and 4/8, 8/8, 7/8, 7/8 and 8/8, respectively.The calculated acute oral LD50 for males was 2000 (95% Cl 1535-2606) mg/kg bw, and the calculated acute oral LD50 for females was 1060 (95% Cl 853-1318) mg/kg bw.

Clinical signs: At the lowest dose 1.0 g/kg in males and 0.63 g/kg in females, animals were prone or ataxic for the remainder of the day after dosing. Survivors recovered in the next day and appeared normal from day two and three, respectively, for the remainder of the study. At higher doses similar signs occurred and soft stools were relatively frequent. Other signs that occurred sporadically were e.g. chromodacryorrhea, clonic convulsions, and wetness of the fur around the mouth. All surviving animals gained weight in a normal pattern.

Necropsy: No signs of systemic toxicity were found in animals necropsied at termination. Common signs in animals that died were yellow fluid in the stomach (probably test article) and reddish fluid in the intestines. In two animals red lining of the intestines is observed from which one animal also showed red lining of the stomach. Furthermore in one animal black fluid in the intestines was observed and in one animal autolysis of tissue in other than standard examined tissues.

Supporting 2nd study (which is part of the report in which the key study is presented) An additional groups of 8 females were dosed 0.63, 0.79, 1.0, 1.26 and 1.59 g/kg bw and a mortality rate of 1/8, 5/8, 7/8, 8/8 and 5/8 animals was found, respectively.The LD50 in the additional females was not calculated in absence of a clear dose response. A new study in females was performed.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
Value:
1 060 mg/kg bw

Additional information

Acute toxicity: Oral

Information for oral acute toxicity is available from one key toxicity study in male and female rats and two supporting studies in female rats only. In the key study a LD50 of 2000 and 1060 mg/kg bw is calculated for males and females, respectively. In the second study the LD50 for females there was no clear dose response and an LD50 could not be calculated. In the third study the LD50 in females was 2020.0 mg/kg bw. The doses and mortality are summarized in the table below.

Dose

Mg/kg bw

Mortality males

Mortality females

Dose in mg/kg bw

Mortality

females

Dose in mg/kg bw

Mortality

females

Key study

 

 

Supporting study

 

Supporting study

 

 

 

 

 

 

590

1/10

 

 

 

630

1/8

 

 

 

 

 

790

5/8

 

 

1000

1/8

4/8

1000

7/8

1000

0/10

 

 

 

1260

8/8

 

 

1400

3/8

8/8

 

 

 

 

 

 

 

1590

5/8

 

 

 

 

 

 

 

1690

1/10

1800

4/8

7/8

 

 

 

 

2400

2/8

7/8

 

 

 

 

 

 

 

 

 

2880

9/10

3200

7/8

8/8

 

 

 

 

 

 

 

 

 

5000

9/10

LD50

2000

1060

LD50

790-1590

LD50

2020

 

The details regarding these studies are described below (Key study and Supporting information).

 

Key study

An acute oral toxicity study was performed according to a method similar to OECD TG 401, not under GLP and therefore receives Kl. 2. A reliable internal protocol was used and the study is well documented. In this study, 80 rats (40 males and 40 females) were administered Dimeth Cyclormol at dose levels of 1.0, 1.4, 1.8, 2.4, and 3.2 g/kg bw resulting in mortality rates of 1/8, 3/8, 4/8, 2/8, and 7/8 for males and 4/8, 8/8, 7/8, 7/8 and 8/8, respectively. The calculated acute oral LD50 for males was 2000 (95% Cl 1535-2606) mg/kg bw, and the calculated acute oral LD50 for females was 1060 (95% Cl 853-1318) mg/kg bw.

Clinical signs: At the lowest dose 1.0 g/kg in males and 0.63 g/kg in females, animals were prone or ataxic for the remainder of the day after dosing. Survivors recovered in the next day and appeared normal from day two and three, respectively, for the remainder of the study. At higher doses similar signs occurred and soft stools were relatively frequent. Other signs that occurred sporadically were e.g. chromodacryorrhea, clonic convulsions, and wetness of the fur around the mouth. All surviving animals gained weight in a normal pattern.

Necropsy: No signs of systemic toxicity were found in animals necropsied at termination. Common signs in animals that died were yellow fluid in the stomach (probably test article) and reddish fluid in the intestines. In two animals red lining of the intestines is observed from which one animal also showed red lining of the stomach. Furthermore in one animal black fluid in the intestines was observed and in one animal autolysis of tissue in other than standard examined tissues.

Supporting 2nd study (which is part of the report in which the key study is presented) An additional groups of 8 females were dosed 0.63, 0.79, 1.0, 1.26 and 1.59 g/kg bw and a mortality rate of 1/8, 5/8, 7/8, 8/8 and 5/8 animals was found, respectively. The LD50 in the additional females was not calculated in absence of a clear dose response. A new study in females was performed.

Supporting information, third study:

A second acute oral toxicity study was performed (IFF, 1980) according to a method similar to OECD TG 401 and under GLP. The study is a pre-guideline study and therefore rated Klimisch 2. In this study, 50 female rats were administered Dimeth Cyclormol at dose levels of 0.59, 1.0, 1.69, 2.88 and 5.0 g/kg bw resulting in mortality rates 1/10, 0/10, 1/10, 9/10 and 9/10, respectively.Clinical signsobserved were ataxia, lethargy or adoption of the prone position. Other signs were e.g. abdominal gripping, oral discharge and lacrimation.All surviving animals gained weight.

Necropsy: No lesions were found in animals necropsied at termination. Many of the animals which died had fluid filled stomachs and intestines, and red stomach linings. One animal also had red lungs and one animal had autolysis in the liver.

Conclusion: Under the conditions of this study the calculated acute oral LD50 for females was 2020 (95% Cl 700-5840) mg/kg bw.

Acute toxicity: Dermal

An acute dermal toxicity study was performed (IFF, 1980) according to a method similar to OECD TG 402 and GLP. In view of the study being a pre-guideline study it is rated Kl. 2. In this study, 8 male and 8 female rats were dosed with the undiluted test substance at 5.0 g/kg bw without occlusion; allowed to remain in contact with the skin and open to the air for 24 hours. Observation period was 14 days. 

Clinical signs:The primary clinical signs which appeared following dosing were lethargy, chromodacryorrhea and chromorhinorrhea. Additionally, two animals became ataxic and had diarrhea. One of these rats recovered on day 3, and the other on day 6. Except for the one which exhibited symptoms up to day 6, all others appeared normal on day 3 and remained healthy throughout the study. Most animals gained weight in a normal manner, two females gained 10 grams or less. Necropsy: At necropsy, none of the animals had any signs indicative of systemic toxicity. No skin irritation was seen after the 14 -day observation period.

Conclusion: The LD50 was > 5000 mg/kg bw. This result does not have an impact on the classification.

Justification for classification or non-classification

Based on the available data, Dimeth Cyclormol needs to be classified for acute oral toxicity (Acute Toxicity Oral, Category 4 / H302: Harmful if swallowed) in accordance with EU CLP (1272/2008/EC and its updates).